1. Field of the Invention
The present invention relates to novel anthracycline antibiotics which are produced by microorganisms belonging to the genus Streptomyces.
2. Description of the Prior Art
As anthracycline type antibiotics, daunomycin (cf. U.S. Pat. No. 3,616,242) and adriamycin (cf. U.S. Pat. No. 3,590,028), obtained from a culture solution of actinomycetes have been hitherto known. These compounds exhibit a broad anti-cancer spectrum against experimental tumors and have been widely utilized as chemotherapic agents against cancers also from a clinical aspect. However, the anti-cancer action of daunomycin and adriamycin is not necessarily satisfactory though they show a considerably potent action. Thus, attempts to produce various compounds analogous thereto have been made by various means of fermentation, semi-synthesis, conversion using microorganisms and, some anthracycline antibiotics have already been proposed (for example, Published Examined Japanese Patent Application No. 34915/76 aclacinomycins A and B), T. Oki et al, The Journal of Antibiotics, vol. 33, pages 1331-1340, F. Areamone, Topics in Antibiotic Chemistry, vol. 2, pages 102-279, published by Ellis Horwood Limited, Published Unexamined Japanese Patent Application No. 56494/82 (4-demethoxy-11-deoxydaunomycin, etc.), Published Unexamined Japanese Patent Application No. 15299/81 (rhodomycin series antibiotics), etc. are disclosed).
As anthracycline antibiotics as anti-cancer agents, a variety of analogous compounds have been proposed as described above; a part of them has been widely used for clinical purpose and provided for clinical test.
However, none of them is satisfactory both in toxicity and anti-cancer action. Further, results of anti-tumor agents obtained with in vitro tests and animal tests are not always reflective directly on anti-cancer action against human and therefore, investigations are required from various viewpoints. For this reason, it has been desired to propose compounds belonging to a further new class, with respect to anthracycline antibiotics which have been evaluated in a way.